CH. 12 SOLIDS & MODERN MATERIALS

CLASSIFICATION STRUCTURE >unit cell

RECALL

3 physical states solid -- liquid -- gas

Diamond -- WaxMallable-Ductile --- BrittleType of bonds

Metallic Solids-metallic bonding, sea “e-”-strong w/o brittle-conduct electricity

Ionic Solids-electrostatic attraction-cation/anion

Covalent Network-covalent bonds-hardness/semiconductor prop

Molecular Solids-intermol forces, weak-soft/lowm.p.

STRUCTURECrystalline solids Amorphous solids>ordered arrangement >random arrangement>flat surfaces >no defined surface/shape>regular shapes; rhombic, cubic,

Unit Cell – repeating unit of unique arrangement; parallelogram of size & shape defined by vectorsCrystal Lattice – geometric pattern of ptsLattice Pts – pts in crystal w/ same environmentPrimitive – lattice pt each corner

Unit Cell>cells fit together to cover area w/ no gaps, thus square, rectangle, hexagon, rhomboid, parallelogram>Other polygons leave gaps

LATTICES2D – 5 shapes 2 vectors

vary length vectors = length vector90o not 120o 90o

5th Rhombic Lattice= vector length, but angle not 90o or 120o

LATTICES3D – 7 lattices 3 vectors

Centered LatticesAdditional lattice pts at specific locations in unit cell

METALLIC SOLIDS

Bonding too strong for dispersion, not many val e- to form covalent bonds, sometallic bonding due to delocalized e-

malleable - ductile behavior indicates slip pass each other

e-

e-

e-

e-

e-

e-

Rare Fe, Cr, Al, Pb, Cu,radioactive, Po Na, W Ag, Au

Close Packing>short valence e-

>efficient way to layer

ALLOYS>2+ elements w/ properties of a metal>used to modify pure metal elements>4 categories substitutional, interstitial, heterogeneous, intermetallic mixtures

SUBSTITUTIONAL